When ducks go looking for a mate, flashy plumage may be of no interest to them at all.

Scientists have shown that the more "caring and sharing" drakes on the river are the ones that seem to turn female heads.

The researchers from Cambridge University, UK, found that females that mated with their preferred drake laid bigger eggs. It means the chicks are likely to have a better start in life because the offspring that hatch from larger, heavier eggs tend to be in a better condition when they emerge.

The research could have implications for farm management as it suggests that letting farm animals choose their own mate - which is often considered a more ethical way to breed farmed animals - may also be a more productive one as well.

Early bird

The observations come from four years of work by Emma Cunningham and Andrew Russell and are reported in the journal Nature.

Pairing with dominant males will mean more food

"In many different animals, 'attractive' males often father healthier offspring than other males," said Dr Cunningham. "It was presumed this was because they have 'good genes', which they pass onto their offspring. But our study, which has focused on the mallard duck, has shown it can all depend on how much the female likes her partner."

The research was centred on a large river running through the Chatsworth Estate in Derbyshire. The scientists studied more than a hundred tagged, wild birds and a slightly smaller number in a penned breeding programme.

The work suggested that "attractive" males were the ones that hatched very early in the spring. Since the early bird catches the worm, these ducks were generally in much better condition than other males. They were probably the more dominant drakes and better able to patrol and defend feeding areas.

Old arguments

"Associating with these males means the females can afford to lay a bigger egg because they will have more access to food," Dr Cunningham told BBC News Online. "However, it is not a direct effect because even if you keep the food the same for all the females you still get an effect.

"But presumably, over the years through natural selection, because these more attractive males can offer them more food, they know they can safely lay bigger eggs without leaving themselves in very bad condition."

The study raises once again the old arguments about the importance of environment versus genetics. This research shows that the desire to find "good genes" in a mate may not always be as great as some scientists believe.

"The way the environment can interact with genes is really much more complex." said Dr Cunningham. "Things like maternal investment can completely wash away the effects of any genes, simply because they are so much stronger."